Edit 7/16/2024: The cucumber beetles finally showed up this morning. And, we had a few Japanese beetles. Still no sign of the squash vine borer, though, despite having several varieties of cucurbits in my garden.
Where are the bugs?
I guess I shouldn’t complain, but certain of my garden insect pests are missing. And — see below — that’s likely due to drought in this area.
It’s now way past time for Japanese beetles (left), cucumber beetles (center), and squash vine borers (right) to show up. These should all appear when we’ve reached ~1000 growing-degree-days of accumulated warmth for the year. That occurred in this area almost two weeks ago. We’ve now accumulated somewhere in excess of 1300 growing-degree-days of warmth. So these pests are way overdue, no matter how I figure it.
Source: Cornell University.
And yet, so far, I’ve seen a total of three Japanese beetles. Cucumber beetles — normally found in my squash blossoms every morning — are nowhere to be seen. Ditto for the squash vine borer, which should be fairly easy to spot due to its bright orange coloring.
Does that mean they aren’t going to show up this year? Or are they merely delayed for some reason?
A clue from Purdue U
Nothing heralds summer like the hum of Japanese beetles ravenously descending on a flower garden. Cool weather this spring has slowed emergence of adults from the soil. Heavy spring rains early followed by relatively drier weather in late June, may have trapped adult Japanese beetles under a crusty layer of hardened soil. Due to their large numbers in many parts of Indiana last year, they are very likely just waiting for a good rain to soften the surface, so they can dig themselves into the light of day and on to your flowers. So, if we get a little more rain by the time this article comes out, we are likely to be awash in adult beetles.
Source: Purdue University landscaper report, emphasis mine.
The paragraph above was for 2022, for Indiana.
But it describes 2024 in Virginia well. This spring was characterized by plenty of rain, followed by drought that kicked in just as we were approaching 1000 degree-days of warmth.
For Japanese beetles, at least, the bottom line is that they have probably been delayed by the drought. For the other two, by analogy, it’s plausible that they, too, have been delayed by crusty topsoil resulting from weeks of no rain.
The bottom line is that I can’t count on having dodged these pests for the year. Likely they are just waiting for enough rain to soften the topsoil, so they can dig themselves up into the light of day.
We had a welcome half-inch of rain last night. Perhaps I’ll be seeing these old friends soon.
